Environmental Biology Flashcards
(91 cards)
What is environment
The environment is the complex of physical, chemical, and biotic factors that act upon an organism or an ecological community and ultimately determine its form and survival
Environmental biology
Is the study of biological components of the environment and its relationship with each other and with abiotic components.
Organisational levels of the environment and definitions
Individual(organism) - Any organism or living thing which has its own characters in physiology, evolution and behaviour in relation to environmental factors
Population - Group of individuals of the same species, living in the same area and producing fertile offsprings through interbreeding.
Community - collection of populations of different species living in the same area
interacting with each other.
Ecosystem - collection of communities as well as the abiotic factors with
which they interact.
Biosphere - entire portion of Earth that is inhabited by life.
Components of the environment
Abiotic components - non-living components. e.g: water, air, light, temperature, nutrients, sunlight, soil. usually resources are obtained from lithosphere, atmosphere and hydrosphere.
Biotic components - primary producers, consumers and decomposers
Niche and habitat
Niche is the role that a particular organism plays in the ecosystem
Habitat is the physical area where a species lives
Interactions between abiotic and biotic components of the environment
Biotic-biotic interactions- e.g. competition, feeding relationships, symbiotic relationships
between individuals and species.
Biotic-abiotic interactions- e.g. water uptake of plants from soil
Abiotic-abiotic interactions-e.g. chemical reactions occurring in the soil.
What are trophic levels
The producers and consumers in ecosystem can be arranged into several feeding groups, each known as trophic level (feeding level).
producers represent the first trophic level, herbivores represent the second trophic level, primary carnivores represent the third trophic level and top carnivores represent other levels.
Food chain
A food chain is a linear sequence of organisms through which nutrients and energy pass from one trophic level to another trophic level of an ecosystem beginning with a primary producer.
Primary production
is the amount of organic matter produced by autotrophs in a given area during a given period of time. (Unit: gm-2day -1or kg ha-1year -1)
ha = hectare
3 types of food chains
Grazing food chains - starts with a primary producer
Detritus food chain - Starts with detritus (dead remains of an organism)
Parasitic food chains - Starts with a host organism
In a forest ecosystem, most of the energy is transmitted in detritus food chains whereas the most amount of energy is transmitted in ocean ecosystems through grazing food chains
Food web
In a natural ecosystem isolated food chains does not exist
The food web is an interconnected feeding relationships in an ecosystem.
Energy loss along food chains
The flow of energy along a food chain is always unidirectional.
At each trophic level in the food chain, a considerable fraction (about 90 %) of the potential energy is lost as heat and respiration. As a result, organisms in each trophic level pass on lesser energy (about 10 %) to the next trophic level than they actually receive.
This limits the number of trophic levels in any food chain to four or five.
The most ecologically efficient food chain is the shortest one.
Ecological pyramids
The pyramids are a graphical representation which depicts the number of organisms, biomass and productivity at each trophic level.
The higher the steps in the ecological pyramid the lower will be the number of individuals and the larger their size.
The concept of ecological pyramid was developed by Charles Elton; these pyramids are also known as Eltonian pyramids.
Types of ecological pyramids
Pyramid of energy - represents the amount of energy at different trophic levels. As there is considerable loss of energy during the flow of energy from organism to other, the energy pyramid
always upright and vertical.
Pyramid of numbers - The pyramid of numbers depicts the relationship in terms of the number of producers, herbivores and the carnivores at their successive trophic levels. 2 types as upright (producer, herbivore, carnivore) and inverted (host, parasites)
Pyramid of biomass - n this pyramid there is a gradual decrease in the biomass from the producers to the higher trophic levels. 2 types as upright and inverted.
Biome
A biome is a large geographical area which is classified based on the predominant vegetation adapted to that particular environment.
Tropical forests
This biome is distributed close to the equator and extends to the sub equatorial areas
The average annual rainfall in tropical rain forests is about 2000 -4000 mm and in tropical dry forests it is about 1500- 2000 mm. Seasonal rainfall with a dry season of 6-7 months is prominent in the dry forests and a fairly constant rainy season is prominent in the rainforests.
average temperature of 25 -29 °C, whereas in the tropical dry forests it may reach up to 33 °C.
In tropical rainforests an emergent layer, canopy and sub canopy layers are visible. Evergreens are prominent in tropical rain forests whereas in dry forests leaves of deciduous species fall in the dry season. Epiphytes are common in this biome.
Highest diversity of plants and animals out of all terrestrial biomes
Tropical forests
Savana
Savanna is spread close to the equator and subequatorial areas.
The average annual rainfall in this biome is around 300-500 mm. A prolonged dry season of approximately 8-9 months is prominent. The average temperature range is 24- 29 °C. However in subequatorial areas seasonal variations may occur. Many insects (termites), lions and zebras are the common animals which are adapted with long range vision and long distance migration. Tall grass cover with scattered trees.
Desert
Desert is a temperate or tropical biome
annual average rainfall is less than 3000 mm per year.The temperature varies seasonally and daily and exceeds 50 °C in hot deserts while in cold deserts it drops below -30° C. Water conservation is a prominent feature and contains many nocturnal animal species
Adaptations of desert plants
Succulent plant body
Most plants have C4 pathway of photosynthesis
Deep roots in shrubs
Presence of spines and thorns
Presence of toxins in leaves
Chaparral
Chaparral occurs in mid latitude coastal regions
Chaparrals receive an average annual rainfall of 300-500 mm. They experience rainy winters and dry summer. The average temperature is between 10 to 12 °C but can reach up to 40 °C.
Chaparral is vulnerable to fire caused by human activities.
Adaptations of plants found in chaparral
Seed germination occurring only after a hot fire.
fire resistant roots.
Uses of food stored in the fire resistant roots for resprouting after a fire.
Quick re -sprouting enables usage of nutrients released by the fire.
Tough evergreen leaves in woody plants to survive in droughts.
Temperate grasslands
These grasslands occur under temperate climatic regimes that are intermediate to those that support forest and desert.
The average rainfall is 300 to 1000 mm per year.
During winter seasons the average temperature falls below -10 °C and in summer it is about 30 °C.
The prairie is often divided into three types according to height of the dominant vegetation—tall-grass, mixed-grass, and short-grass.
The tall-grass prairie is now an endangered natural ecosystem
Temperate broadleaf forests
Distribution of temperate broadleaf forests are at mid latitudes in the northern hemisphere. The average annual precipitation is between 700 to 2000 mm.
Average temperature during winter is zero while in summer it is up to 35 °C
The dominant trees are mostly deciduous. A vertical layering (stratification) can be seen in temperate broadleaf forests. They are closed canopy layer, one or two strata of understory trees, shrub layer and herb layer. There are only few epiphytes can be found.
